When a work vehicle such as a wheel loader performs an excavation work, if a travel driving force is too large, a working device load is made excessively large and hence a working device speed is reduced or tires slip, which hence impairs a work efficiency. On the other hand, if the travel driving force is too small, a bucket cannot be sufficiently penetrated into an object to be excavated such as the earth and sand, which reduces an excavation volume and impairs the work efficiency.
In patent literature 1 is described such a travel control device of a work vehicle that reduces a maximum value of a displacement volume of a hydraulic motor to a minimum limit value corresponding to a maximum load pressure of a working hydraulic circuit if a load pressure of a working hydraulic circuit is made larger than a specified value.